Paternal Age, Social Development, and Behavioral Conditions

Advanced age of a pregnant mother is something that often worries people, because risk of chromosomal problems is well established, and maybe also because the profound influence of the maternal environment on embryonic and fetal is intuitive. But for decades paternal age, and its effects, have been a hot topic of scientific investigation. A new study reveals that the age of the father at conception influences the social development of his children –how well, and in what manner, they relate to others. This adds to a growing body of research a suggesting that having an older father could be a risk factor for development of some psychiatric conditions, including autism spectrum disorder (ASD), and schizophrenia.

The new study is different, because the focus, social development, really is outside the realm of abnormal conditions. One can be outgoing, pleasant, responsive to body language, and responsive other people to varying degrees, without having a behavioral disorder, or a social problem requiring treatment. But schizophrenia and ASD both are developmental disorders that impact social function. Over the decades, researchers and behavioral clinicians settled on the term ASD based on the realization that features of autism occur along a spectrum of severity. Moving from severe to mild autism, one reaches a point of social interaction that we cannot call abnormal. Rather, it is a variation on the societal norm. With a psychotic disorder such as schizophrenia, things are a little more precise; one cannot be mildly schizophrenic, because diagnosis depends on presence of features, such as delusions and hallucinations. Nevertheless, with both ASD and schizophrenia, abnormal social interaction is a very visible part of the picture, but the degree of abnormality varies, and at the mild end blends in with social behaviors of people who are psychologically normal.

In addition to schizophrenia and ASD, researchers have looked for associations between paternal age (at conception and at birth) and other conditions, such as depression, obsessive-compulsive disorder, and attention deficit disorder, but these other conditions do not show as strong an association with paternal age as ASD and schizophrenia do. When it comes to the new study, looking at social behavior outside of abnormal conditions, both old and young paternal age have noticeable effects. Children of very young fathers actually start to engage socially with others very early, but, as they grow up, their social skills do not improve as quickly as those of children with older fathers. So, in a sense, the children of older fathers catch up. Clearly, this means that any connection between the rate of social development and risk of ASD and schizophrenia must be complex.

In any study involving paternal age, there always is a possibility that what you’re measuring is really the result of some other thing that is connected with father’s age. The obvious one is maternal age. If a father is older, the mother also is likely to be older, so the research studies must account for this, and they do. But there is another factor that can confuse the issue, namely social development of the father himself. If a child’s social development is relatively slow, it could be that the father was genetically prone to slow development, and that’s why he got into a relationship late and had children late. Such a genetic effect would be really hard to distinguish from an effect produced by the father on his sperm cells, because of his age when he produced them.

Dr. David Warmflash is a science communicator and physician with a research background in astrobiology and space medicine. He has completed research fellowships at NASA Johnson Space Center, the University of Pennsylvania, and Brandeis University. Since 2002, he has been collaborating with The Planetary Society on experiments helping us to understand the effects of deep space radiation on life forms, and since 2011 has worked nearly full time in medical writing and science journalism. His focus area includes the emergence of new biotechnologies and their impact on biomedicine, public health, and society.